The Influence of Granulometric Properties and Drying Conditions on the Drying Kinetics of a Nonhygroscopic Material

A. Sander, B. Cerjak and B. Domitrović

Abstract
The influence of granulometric properties of the material and of the operational conditions on the drying kinetics of nonhygroscopic material was studied. Four fraction sizes of dolomite were chosen and dried in four dryers by different heating methods. Dolomite was dried in a microwave dryer under different microwave heating powers. During convective drying the effects of temperature and superficial air velocity were monitored. Vacuum drying was carried out at different temperatures and pressures. Page’s model has shown to be successful in describing the drying kinetics throughout the entire drying operation, irrespective of the heating mode. Heat intensity (ϑ, Pm), superficial air velocity and particle size had influence on the drying kinetics. The process was facilitated by higher temperatures and superficial air velocity, higher intensity of microwave radiation and bigger particles. Change of pressure in the vacuum dryer had no significant effect on the drying kinetics under the chosen operating conditions.

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Keywords
Convective drying, drying kinetic, mathematical models, microwave drying, vacuum drying